1. Field of the Invention
The present invention relates generally to data processing, and more particularly but not exclusively to electronic mails.
2. Description of the Background Art
Electronic mail (“email”) has become a relatively common means of communication among individuals. Among its advantages, email is relatively convenient, fast, and cost-effective compared to traditional mail. It is thus no surprise that a lot of businesses and home computer users have some form of email access.
An email server may be employed to store and distribute emails. Each user having an email account with the email server has a corresponding email address. The email server receives inbound emails and stores them by email address. The user associated with an email address may employ an email client to retrieve his email from the email server.
In some applications, it is important to know if an inbound email is for a valid (i.e., has a corresponding email account) email address associated with the email server. For example, some organizations may have policies controlling receiving of emails by particular email addresses. As another example, an intermediate node (e.g., email gateway) may perform security actions on an email depending on whether or not the email is going to a valid email address in the email server. Therefore, a technique for determining valid email addresses associated with an email server is generally desirable.